Field of the Invention
The present invention relates to an organic light emitting device, and more particularly, to a white organic light emitting device which can improve abnormal light emission.
Description of the Related Art
In recent years, as the world entered the information age, the field of display devices for visually displaying electrical information signals has developed rapidly. Thus, various flat panel display devices have developed in the areas of, such as thinning, weight lightening, and consuming low power.
Specific examples of the flat panel display devices include a Liquid Crystal Display (LCD) device, a Plasma Display Panel (PDP) device, a Field Emission Display (FED) device, and an Organic Light Emitting Display (OLED) device.
In particular, the OLED device is a self-light emitting device that has a high response time, a high emission efficiency, a high luminance, and a wide viewing angle as compared with the other flat panel display devices.
An organic light emitting device includes an organic emitting layer between two electrodes. An electron and a hole are injected into the organic emitting layer from the two electrodes and an exciton is formed by combining the electron and hole. Further, the organic light emitting device uses a principle in which a light is emitted when the exciton makes transitions from an excited state to a ground state.
The OLED device does not need a separate light source unlike a liquid crystal display (LCD) device, and, thus, the OLED device can be manufactured into a lightweight and thin form. Further, the OLED device is advantageous in terms of power consumption since it is driven with a low voltage. Also, the OLED device has excellent color expression ability, a high response time, a wide viewing angle, and a high contrast ratio (CR). Therefore, the OLED device is regarded as a next-generation display device.
As high-resolution display devices develop, the demand for higher number of pixels per unit area and a higher luminance has been increased. However, in a light emitting structure of the OLED device, there is a limitation in luminance per unit area. Also, an increase in driving voltage causes a decrease in the reliability of an organic light emitting device and an increase in power consumption.
Accordingly, it is necessary to overcome the limitations in emission efficiency and lifespan of an organic light emitting device that hinder a quality and productivity of the OLED device. Thus, various studies for developing an organic light emitting device capable of improving emission efficiency and a lifespan have been conducted.